相邻腹杆刚度对桁架受压腹杆计算长度的影响

以经典的刚架弹性稳定理论以及相关研究成果为基础,推导了考虑节点刚度和相邻腹杆刚度对受压腹杆影响的杆件群稳定方程以及腹杆计算长度系数计算方程,给出了可供工程使用的桁架腹杆计算长度用表。和现有的腹杆计算长度系数计算方法相比较,本文建议的计算方法更具有一般性。计算分析结果表明,考虑计算节点处相邻腹杆刚度的约束作用后,桁架中间受压腹杆的计算长度有所减小;在大多数刚度比范围内,按本文方法计算的中间和端部受压腹杆的计算长度系数比现行规范的取值小。     

Moving average threshold heterogeneous autoregressive (MAT-HAR) models

We propose moving average threshold heterogeneous autoregressive (MAT-HAR) models as a novel combination of heterogeneous autoregression (HAR) and threshold autoregression (TAR). The MAT-HAR has multiple groups of lags of a target series, and a threshold term can appear in each group. The threshold is a moving average of lagged target series, which guarantees time-varying thresholds and simple estimation via least squares. We show via Monte Carlo simulations that the MAT-HAR has sharp in-sample and out-of-sample performance. An empirical application on the industrial production of Japan suggests that significant threshold effects exist, and the MAT-HAR has a higher forecast accuracy than the HAR.     

Spatial and Temporal Response of Equatorial Ionization Anomaly to the 17 March 2015 Storm from Global Ionosphere Map

The responses of Equatorial Ionosphere Anomaly (EIA) to the storm occurred on 17 March 2015 were studied using Global Ionosphere Map (GIM). The variations of Total Electron Content (TEC), latitudinal TEC gradients and the rate of latitudinal TEC gradients in EIA regions were investigated in 75°E, 110°E and -60°E longitudinal sectors. The results from the GIM data showed that the distributions of the latitudinal gradient of TEC became monotonous in three longitudes on 18 March (the first day of the recovery phase), but the variations were different. On 18 March, the magnitudes of latitudinal gradients decreased in spatial and temporal in 75°E and 110°E, which means the EIA was suppressed during the recovery phase of the storm, especially in 110°E. The magnitudes of latitudinal TEC gradients showed an obvious increase in spatial and temporal in -60°E. The SAMI2 reproduced the suppression of EIA with a disturbance dynamo electric field, which indicated that the physical process controlled the behaviors of the plasma during the recovery phase of the storm.     

Photo-improved hydrogen evolution reaction activity of the Pt/CdS electrocatalyst

The effect of CdS content on the photo-induced improvement of hydrogen evolution reaction activity of the Pt/CdS electrocatalyst was investigated. Although the electrons transferred from CdS to Pt in the Pt/CdS electrocatalyst increased with the CdS content under illumination, the electrochemical active surface area of the Pt/CdS electrocatalyst decreased with the CdS content, resulting that the photo-induced improvement of hydrogen evolution reaction activity of the Pt/CdS electrocatalyst decreased with the CdS content.     

传递矩阵法在电机系统振动特性研究中的应用

应用传递矩阵法对大型发电机机座横向振动特性进行了初步估算，并与ＳＡＰ程序计算结果进行比较．     

烯(火圣)醛化和羰化的新催化剂

研究了钌簇合物Ru_1(CO)_(12),H_4Ru_4(CO)_(12)[PPN][HRu_1(CO)_(11)],[PPN][H_3Ru_4(CO)_(12)](PPN=[(Ph_2P)_2N]~)和Ru_2(CO)_2.(dpm)_3(dpm=ph_2p-m-C_4H_4SO_3Na)等摧化乙烯的醛化,报道了可溶性的Ru_3(CO)_2(dpm)在水溶液中催化丙烯和乙烯的醛化、羰化的性能,在反应温度120℃,反应气体总压为2.7～5.OMPa的条件下,丙烯和乙烯的醛化活性随反应温度、催化剂浓度和气体分压(CO/H_2=1:1)的提高而提高,温度的变化对活性的影响最明显,溶液的酸碱性也影响催化活性,中性对反应最有利,添加无机和有机卤化物显著地影响乙烯的醛化活性和产物分布,乙烯羰化生成二乙基酮的选择性高达52.7％,其反应前后的钉簇合物催化剂分别经IR和XPS表征,讨论了可能的催化活性物种。     

过渡态理论的发展(一)

本文扼要地介绍了经典过渡态理论的发展及现状,集中叙述了过渡态理论中的一些基本概念和理论建立过程中的主要思想和方法,本文不涉及理论的应用。     

劈裂灌浆技术在水库土坝加固中的应用

通过对神山水库土坝进行劈裂式灌浆的施工，总结了采用劈裂灌浆技术进行加固的施工工艺及施工方法。